Modeling the Impact of Salinity Variations on Aquatic Environments: Including Negative and Positive Effects in Life Cycle Assessment.

Salinity is changing in aquatic systems due to anthropogenic activities (like irrigation or dam management) and climate change. Although there are studies on the effects of salinity variations on individual species, little is known about the effects on overall ecosystems, these impacts being more uncertain in transitional waters such as estuaries or fiords. The few works that do address this topic have considered these impacts using ecotoxicity models. However, these models state that an increase in the concentration of a pollutant generates an increase in the impacts, disregarding the effects of water freshening. The present research work introduces a general framework to address the impacts of salinity variations, including emission-related positive effects. We validated this framework by applying it to an estuarine area in Galicia (northwestern Spain), where sharp drops in the salt concentration have caused mass mortalities of shellfish in recent decades. This research work addresses for the first time the potential effects on the environment derived from a decrease in the concentration of essential substances, where the effects of an emission can also generate positive impacts. Moreover, it is expected that the framework can also be applied to model the environmental impacts of other essential substances in life cycle assessment (LCA), such as metals and macronutrients.

A Regionalised Life Cycle Assessment Model to Globally Assess the Environmental Implications of Soil Salinization in Irrigated Agriculture.

We present a global, locally resolved life cycle assessment (LCA) model to assess the potential effects on soil quality due to the accumulation of water-soluble salts in the agricultural soil profile, allowing differentiation between agricultural practices. Using globally available soil and climate information and crop specific salt tolerances, the model quantifies the negative implications that salts in irrigation water have on soil quality, in terms of change in the soil electrical conductivity and the corresponding change in the amount of crops that can be grown at increasing soil salinity levels. To facilitate the use of the model, we provide a life cycle inventory tool with information on salts emitted with irrigation water per country and 160 crops. Global average soil susceptibility is 0.19 dS/m per grams of salt in 1 m3 of soil, and the average resulting relative crop diversity loss is 5.7 × 10-2 per grams of salt in 1 m3 of soil. These average values vary tangibly as a function of the location. In most humid regions worldwide, the characterization factor is null, showing that in these cases soil salinization due to irrigation does not contribute to soil degradation. We displayed how to apply the model with a case study. The model serves for guiding decision-making processes toward improving the sustainability of irrigated agriculture.

A Multimedia Hydrological Fate Modeling Framework To Assess Water Consumption Impacts in Life Cycle Assessment.

Many new methods have recently been developed to address environmental consequences of water consumption in life cycle assessment (LCA). However, such methods can only partially be compared and combined, because their modeling structure and metrics are inconsistent. Moreover, they focus on specific water sources (e.g., river) and miss description of transport flows between water compartments (e.g., from river to atmosphere via evaporation) and regions (e.g., atmospheric advection). Consequently, they provide a partial regard of the local and global hydrological cycle and derived impacts on the environment. This paper proposes consensus-based guidelines for a harmonized development of the next generation of water consumption LCA indicators, with a focus on consequences of water consumption on ecosystem quality. To include the consideration of the multimedia water fate between compartments of the water cycle, we provide spatial regionalization and temporal specification guidance. The principles and recommendations of the paper are applied to an illustrative case study. The guidelines set the basis of a more accurate, novel way of modeling water consumption impacts in LCA. The environmental relevance of this LCA impact category will improve, yet much research is needed to make the guidelines operational.

Understanding the LCA and ISO water footprint: A response to Hoekstra (2016) "A critique on the water-scarcity weighted water footprint in LCA".

Water footprinting has emerged as an important approach to assess water use related effects from consumption of goods and services. Assessment methods are proposed by two different communities, the Water Footprint Network (WFN) and the Life Cycle Assessment (LCA) community. The proposed methods are broadly similar and encompass both the computation of water use and its impacts, but differ in communication of a water footprint result. In this paper, we explain the role and goal of LCA and ISO-compatible water footprinting and resolve the six issues raised by Hoekstra (2016) in "A critique on the water-scarcity weighted water footprint in LCA". By clarifying the concerns, we identify both the overlapping goals in the WFN and LCA water footprint assessments and discrepancies between them. The main differing perspective between the WFN and LCA-based approach seems to relate to the fact that LCA aims to account for environmental impacts, while the WFN aims to account for water productivity of global fresh water as a limited resource. We conclude that there is potential to use synergies in research for the two approaches and highlight the need for proper declaration of the methods applied.

Measuring Outcomes: Pain and Quality of Life 48 Months After Acute Postoperative Total Knee Prosthetic Joint Infection.

BACKGROUND: Measuring HRQOL is simple, inexpensive, permits the health status to be measured over time, and is useful to compare or initiate treatments and evaluate results, facilitating homogenization in patient inclusion. OBJECTIVES: To evaluate disease-specific and generic HRQOL and influence of associated factors in patients undergoing open debridement for acute postsurgical knee prosthetic joint infection after TKR at 12 and 48 months after completing antibiotic treatment and considered cured of infection. METHODS: Health-related quality-of-life measures were administered at baseline (WOMAC) and 12 and 48 months (WOMAC and SF-36) in patients with prosthesis retention, no symptoms of infection, and CRP (≤ 1 mg/dL). RESULTS: Thirty patients were included, and 24 were evaluated at 48 months. WOMAC scores improved significantly (P < 0.01) at 12 and 48 months. The effect size was 0.72 for stiffness, 2.01 for pain, and 2.15 for function. At 48 months, improvements were greater (P < 0.02) except for stiffness. The most frequently isolated microorganisms were Staphylococcus aureus (14 patients) and coagulase-negative staphylococci (9 patients). SF-36 physical role, bodily pain, emotional role, and mental health dimension scores at 12 and 48 months were significantly worse in patients with isolates of Staphylococcus aureus (P < 0.05). CONCLUSIONS: Health-related quality-of-life measures detected significant differences in outcomes in patients infected by S. aureus compared with patients infected by other microorganisms. HRQOL measures may provide useful complementary information on outcomes after acute postoperative infection.

Improvement of agricultural life cycle assessment studies through spatial differentiation and new impact categories: case study on greenhouse tomato production.

This paper presents the inclusion of new, relevant impact categories for agriculture life cycle assessments. We performed a specific case study with a focus on the applicability of spatially explicit characterization factors. The main goals were to provide a detailed evaluation of these new impact category methods, compare the results with commonly used methods (ReCiPe and USEtox) and demonstrate how these new methods can help improve environmental assessment in agriculture. As an overall conclusion, the newly developed impact categories helped fill the most important gaps related to land use, water consumption, pesticide toxicity, and nontoxic emissions linked to fertilizer use. We also found that including biodiversity damage due to land use and the effect of water consumption on wetlands represented a scientific advance toward more realistic environmental assessment of agricultural practices. Likewise, the dynamic crop model for assessing human toxicity from pesticide residue in food can lead to better practice in pesticide application. In further life cycle assessment (LCA) method developments, common end point units and normalization units should be agreed upon to make it possible to compare different impacts and methods. In addition, the application of site-specific characterization factors allowed us to be more accurate regarding inventory data and to identify precisely where background flows acquire high relevance.

Estimating water consumption of potential natural vegetation on global dry lands: building an LCA framework for green water flows.

This study aimed to provide a framework for assessing direct soil-water consumption, also termed green water in the literature, in life cycle assessment (LCA). This was an issue that LCA had not tackled before. The approach, which is applied during the life cycle inventory phase (LCI), consists of quantifying the net change in the evapo(transpi)ration of the production system compared to the natural reference situation. Potential natural vegetation (PNV) is used as the natural reference situation. In order to apply the method, we estimated PNV evapotranspiration adapted to local biogeographic conditions, on global dry lands, where soil-water consumption impacts can be critical. Values are reported at different spatial aggregation levels: 10-arcmin global grid, ecoregions (501 units), biomes (14 units), countries (124 units), continents, and a global average, to facilitate the assessment for different spatial information detail levels available in the LCI. The method is intended to be used in rain-fed agriculture and rainwater harvesting contexts, which includes direct soil moisture uptake by plants and rainwater harvested and then reused in production systems. The paper provides the necessary LCI method and data for further development of impact assessment models and characterization factors to evaluate the environmental effects of the net change in evapo(transpi)ration.

Assessing water deprivation at the sub-river basin scale in LCA integrating downstream cascade effects.

Physical water deprivation at the midpoint level is assessed in water-related LCIA methods using water scarcity indicators (e.g., withdrawal-to-availability and consumption-to-availability) at the river basin scale. Although these indicators represent a great step forward in the assessment of water-use-related impacts in LCA, significant challenges still remain in improving their accuracy and relevance. This paper presents a methodology that can be used to derive midpoint characterization factors for water deprivation taking into account downstream cascade effects within a single river basin. This effect is considered at a finer scale because a river basin must be split into different subunits. The proposed framework is based on a two-step approach. First, water scarcity is defined at the sub-river basin scale with the consumption-to-availability (CTA) ratio, and second, characterization factors for water deprivation (CFWD) are calculated, integrating the effects on downstream sub-river basins. The sub-river basin CTA and CFWD were computed based on runoff data, water consumption data and a water balance for two different river basins. The results show significant differences between the CFWD in a given river basin, depending on the upstream or downstream position. Finally, an illustrative example is presented, in which different land planning scenarios, taking into account additional water consumption in a city, are assessed. Our work demonstrates how crucial it is to localize the withdrawal and release positions within a river basin.

Global water consumption impacts on riverine fish species richness in Life Cycle Assessment.

Reduced river discharge and flow regulation are significant threats to freshwater biodiversity. An accurate representation of potential damage of water consumption on freshwater biodiversity is required to quantify and compare the environmental impacts of global value chains. The effect of discharge reduction on fish species richness was previously modeled in life cycle impact assessment, but models were limited by the restricted geographical scope of underlying species-discharge relationships and the small number of species data. Here, we propose a model based on a novel regionalized species-discharge relationship (SDR). Our SDR-based model covers 88 % of the global landmass (2320 river basins worldwide excluding deserts and permanently frozen areas) and is based on a global dataset of 11,450 riverine fish species, simulated river discharge, elevation, and climate zones. We performed 10-fold cross-validation to select the best set of predictors and validated the obtained SDRs based on observed discharge data. Our model performed better than previous SDRs employed in life cycle impact assessment (Kling-Gupta efficiency coefficient about 4 times larger). We provide both marginal and average models with their uncertainty ranges for assessing scenarios of small and large-scale water consumption, respectively, and include regional and global species loss. We conducted an illustrative case study to showcase the method's applicability and highlight the differences with the currently used approach. Our models are useful for supporting sustainable water consumption and riverine fish biodiversity conservation decisions. They enable a more specific, reliable, and complete impact assessment by differentiating impacts on regional riverine fish species richness and irreversible global losses, including up-to-date species data, and providing spatially explicit values with high geographical coverage.

Health-related quality of life and direct costs in patients with anterior cruciate ligament injury: single-bundle versus double-bundle reconstruction in a low-demand cohort--a randomized trial with 2 years of follow-up.

PURPOSE: To evaluate health-related quality of life (HRQL) in patients undergoing anterior cruciate ligament (ACL) reconstructive surgery by use of 2 procedures and to estimate the direct costs of surgery. METHODS: We performed a 2-year randomized, prospective intervention study of 2 surgical ACL reconstruction techniques (anatomic single bundle [SB] v double bundle [DB]). Fifty-five consecutive outpatients, with a mean age of 30.88 years, were randomized to SB or DB ACL reconstruction. The Medical Outcomes Study 36-item Short Form Health Survey (SF-36) was used to measure HRQL (primary outcome). ACL injuries were assessed by the International Knee Documentation Committee (IKDC) score (secondary outcome). The use of medical resources and their costs were evaluated. RESULTS: We included 52 patients in the final analyses (23 in the SB group and 29 in the DB group). At baseline, there were no significant differences in study variables. At 2 years of follow-up, there were no significant differences in SF-36 and IKDC scores between groups. However, compared with baseline, the SF-36 physical function, physical role, bodily pain, social function, and emotional role scores were significantly better in the SB group (P < .05), whereas only the physical function dimension score was better in the DB group (P = .047). IKDC scores at 2 years improved significantly in the SB group (P < .001) and DB group (P = .004) compared with baseline. There was a significant correlation between the SF-36 physical function, physical role, and bodily pain dimensions and the IKDC score at 2 years (P < .05). The costs were € 3,251 for the SB group and € 4,172 for the DB group. CONCLUSIONS: HRQL and medical outcomes were similar between SB and DB ACL reconstruction techniques, 2 years after surgery. However, the SB technique was more cost-effective.

[Perception in chronic illnesses: linguistic validation of the revised Illness Perception Questionnaire and the Brief Illness Perception Questionnaire for a Spanish population]. / Percepción en enfermedades crónicas: validación lingüística del Illness Perception Questionnaire Revised y del Brief Illness Perception Questionnaire para la población española.

OBJECTIVE: To obtain adapted versions for the Spanish population of a specific version of the Revised Illness Perception Questionnaire Revised (IPQ-R(e)) and the Brief Illness Perception Questionnaire (BIPQ), conceptually and linguistically equivalent to the original questionnaires. DESIGN: Cultural adaptation of questionnaires: linguistic validation. SETTING: Five primary care centres and a tertiary hospital. PARTICIPANTS: A multidisciplinary team was selected. A pilot study was performed on 30 people with chronic diseases (hypertension, diabetes mellitus, stable ischaemic heart disease, asthma, chronic obstructive pulmonary disease or osteoarthritis) METHOD: The project proceeded in 3 phases: I) Double forward-translation, II) Pilot study and III) Double back-translation. Three consensus meetings were held, one in each phase. Another meeting was held with one of the authors of the original questionnaire, where we knew about a short version, the BIPQ. It was also included in the study. Double forward and back-translations were performed and consensus was reached in both stages. RESULTS: Phase I) The majority of IPQ-R(e) items did not raise problems of translation. Phase II) In the pilot study we detected that patients found some difficulties in connection with the comprehension and self administration of some items. Therefore it was decided to employ trained interviewers, to introduce changes in the IPQ-R(e) format and vocabulary and to adapt a specific version with fewer items that solved most of these difficulties Phase III) Back-translations were very similar to the original version. The BIPQ forward and back-translation process caused no difficulties. CONCLUSIONS: After lingüistic validation, IPQ-R(e) and BIPQ versions conceptually and lingüistically equivalent to original instruments were obtained.

Factors influencing health-related quality of life after TKA in patients who are obese.

BACKGROUND: Although the health-related quality of life (HRQL) for patients who are obese seems to improve after TKA, the magnitude of improvement and the associated factors remain controversial. We previously found body mass index was not associated with changes in HRQL after TKA. QUESTIONS/PURPOSES: The purposes of this secondary analysis were to determine which patient characteristics and surgical factors were associated with worse health status after TKA in patients who are severe or morbidly obese. METHODS: We assessed 60 patients (53 females; mean age, 70 years) 12 months after surgery. The mean number of comorbidities was 2.5. Mean lower limb anthropometric index scores were: suprapatellar, 1.6; infrapatellar, 2; and suprapatellar/infrapatellar, 1.2. Intraoperative difficulty (IOD) was Grade 0, 40%; Grade 1, 48%; and Grade 2, 12%. Ten patients (17%) had complications. We measured HRQL using the disease-specific WOMAC questionnaire. Patient characteristics (sociodemographic variables, BMI, comorbidity, lower limb anthropometry) and surgical factors (IOD, complications, postoperative medical data) were collected. Associations between WOMAC dimension scores at 12 months and patient characteristics and surgical factors were analyzed using linear regression models. RESULTS: Factors associated with worse WOMAC dimension scores in patients who were obese included the number of comorbidities, an infrapatellar index percentile less than 75, IOD Grade 2, and the number of complications after discharge. CONCLUSIONS: For patients with knee osteoarthritis who were severe or morbidly obese, various lower limb anthropometric features, degree of IOD, and postoperative complications negatively influenced postoperative WOMAC scores. LEVEL OF EVIDENCE: Level II Prognostic Study. See Guidelines for a complete description of levels of evidence.

Kynurenic Acid Electrochemical Immunosensor: Blood-Based Diagnosis of Alzheimer's Disease.

Alzheimer's disease (AD) is a neurodegenerative disorder, characterized by a functional deterioration of the brain. Currently, there are selected biomarkers for its diagnosis in cerebrospinal fluid. However, its extraction has several disadvantages for the patient. Therefore, there is an urgent need for a detection method using sensitive and selective blood-based biomarkers. Kynurenic acid (KYNA) is a potential biomarker candidate for this purpose. The alteration of the KYNA levels in blood has been related with inflammatory processes in the brain, produced as a protective function when neurons are damaged. This paper describes a novel electrochemical immunosensor for KYNA detection, based on successive functionalization multi-electrode array. The resultant sensor was characterized by cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS). The proposed biosensor detects KYNA within a linear calibration range from 10 pM to 100 nM using CA and EIS, obtaining a limit of detection (LOD) of 16.9 pM and 37.6 pM in buffer, respectively, being the lowest reported LOD for this biomarker. Moreover, to assess our device closer to the real application, the developed immunosensor was also tested under human serum matrix, obtaining an LOD of 391.71 pM for CA and 278.8 pM for EIS with diluted serum.

Double-bundle versus single-bundle ACL reconstruction using the horizontal femoral position: a prospective, randomized study.

The aim of this study was to evaluate whether anterior cruciate ligament (ACL) reconstruction using the double bundle technique (DB) improves stability in the knee compared with the single bundle technique (SB) with the femoral tunnel in a more horizontal position (2 or 10 o'clock). We conducted a randomized, prospective study. Forty patients were randomized to the DB group (20 patients) and the SB group (20 patients). Four-stranded semitendinosus and gracilis autologous grafts were used in the SB group and in the DB group the conventional four tunnel technique was carried out using the same tendons. The IKDC complete form was used for the preoperative evaluation, and in the follow-up the IKDC subjective knee evaluation form, IKDC current health assessment form and IKDC knee examination form were used. Anteroposterior (AP) laxity was evaluated by standardised and forced radiology in all patients. No significant preoperative between-group differences were found. During the follow-up, no differences were found between groups, except for significant between-group differences (P < 0.05) between the preoperative and postoperative evaluations. The IKDC index also showed significant differences in the 2-year follow-up. Median scores increased from 48 (range 41-54) to 81 (range 75-87) (P = 0.01) in the SB group and from 52 (range 46-58) to 80 (range 72-88) (P = 0.02) in the DB group. There were no significant differences between the groups in terms of functional scores. In conclusion, the 2 and 10 o'clock placements showed no significant differences between SB and DB techniques in the pivot-shift test, manual and radiological anterior posterior laxity and IKDC scores. However, significant between-group differences were found between the preoperative and postoperative evaluations.

Meniscal repair using the FasT-Fix device in patients with chronic meniscal lesions.

The aim of this prospective study was to evaluate meniscal suturing using the FasT-Fix device for chronic meniscal tears. This procedure was carried out on 25 patients between 2006 and 2007. Nineteen patients were male and the median age was 31 (14-47) years. The median waiting time to surgery was 27 (6-80) months and the median follow-up was 20 (14-29) months. Eleven patients (44%) required reconstruction of an associated anterior cruciate ligament (ACL) injury. 20 patients (80%) showed medial meniscus tears. All tears were located in the red zone or red-white zone. According to Barett's criteria, meniscal tear healing was achieved in 21 patients (84%). Lysholm and Tegner scale scores improved from 60 (47-77) preoperatively to 95 (58-100) postoperatively and from 3 (2-6) preoperatively to 6 (3-9) postoperatively, respectively. There were no neurovascular complications. Revision surgery was necessary in one patient, in whom a partial meniscectomy was performed. The results obtained suggest that chronic meniscal tears in the zones described can be healed.

Kynurenic Acid Levels are Increased in the CSF of Alzheimer's Disease Patients.

Kynurenic acid (KYNA) is a product of the tryptophan (TRP) metabolism via the kynurenine pathway (KP). This pathway is activated in neurodegenerative disorders, such as Alzheimer´s disease (AD). KYNA is primarily produced by astrocytes and is considered neuroprotective. Thus, altered KYNA levels may suggest an inflammatory response. Very recently, significant increases in KYNA levels were reported in cerebrospinal fluid (CSF) from AD patients compared with normal controls. In this study, we assessed the accuracy of KYNA in CSF for the classification of patients with AD, cognitively healthy controls, and patients with a variety of other neurodegenerative diseases, including frontotemporal dementia (FTD), amyotrophic lateral sclerosis (ALS), and progressive supranuclear palsy (PSP). Averaged KYNA concentration in CSF was higher in patients with AD when compared with healthy subjects and with all the other differentially diagnosed groups. There were no significant differences in KYNA levels in CSF between any other neurodegenerative groups and controls. These results suggest a specific increase in KYNA concentration in CSF from AD patients not seen in other neurodegenerative diseases.

Role of musculoskeletal disorders as concurrent chronic conditions: are they underestimated in the discharge?

BACKGROUND: Differences in recording concurrent chronic conditions (CCs) could change the weight of the influence of the different CCs on health status. OBJECTIVES: To determine the role of musculoskeletal disorders as concurrent CCs. METHODS: Cross-sectional study. Discharged patients with CCs were selected by random stratification. Sociodemographic and clinical variables, health status (SF-36), type and number of self-reported and hospital discharge summary CCs were recorded. Relationships were analyzed using linear regression models. RESULTS: In the 227 patients included, mean self-reported CCs were 6.22 (SD 3.37) and mean hospital discharge CCs were 3.1 (SD 1.95). The most-frequent self-reported CCs were hypertension 48.4%, back pain 40.4%, neck pain 39.6%, and musculoskeletal disorders 38.4%. The most frequent discharge CCs were arterial hypertensive disease 38.3%, all cancers 22.0%, ischemic heart diseases, and angina 15.9%. Musculoskeletal disorders had the greatest negative influence on SF-36 dimensions (p < 0.05). CONCLUSIONS: Musculoskeletal disorders were underestimated in the discharge summary in comparison with those reported by patients.

Total knee arthroplasty: better short-term results after subvastus approach: a randomized, controlled study.

The purpose of this study was to evaluate the short-term results after performing a total knee arthroplasty (TKA) using two surgical approaches: the subvastus approach (SV) and the conventional parapatellar approach. It was hypothesized that the SV approach would achieve the best short-term benefits. This is a randomized prospective and double-blind study that includes 104 patients. Evaluations were carried out preoperatively, when discharged (5 days) at one, three, and 12 postoperative months. The SV group showed significantly better range of movement and quadriceps extensor force when discharged. Statistically significant differences were found that showed a distinct improvement in favour of the SV group at one month in terms of extensor force and according to the Barthel Index. No significant difference was found between the two groups at the 12 month evaluation. It was concluded that the SV approach offers superior short-term clinical and functional results and it was shown that this approach also offers a significant advantage to the patient in the immediate postoperative period, although these differences tend to disappear over time following TKA. We strongly recommend the SV approach in the majority of TKA.

Water footprint of German agricultural imports: Local impacts due to global trade flows in a fifteen-year perspective.

This study investigates the water scarcity footprint (WSF) trend of German agricultural imports over recent years, following the principles of the ISO 14046 standard on water footprinting. For this purpose, the import statistics of agricultural goods for the years 2000, 2005, 2010, and 2015 was compiled and linked with the irrigation water consumption during their production as well as with the AWARE water scarcity factors of the country of production. Agricultural imports increased by 62% from 22 to 35 million tons during the analysed period. At the same time, the blue water consumption for agricultural production (i.e., irrigation water) decreased by 13% and the WSF declined by 20%, from 119 to 91 km3world-equivalents (world-eq.). The decrease in WSF is caused by drop in the cotton imports, while the WSF associated with the imports of other crops increased by 45%. Product-wise, cotton, nuts, and rice contribute to more than half of the total WSF in all analysed years. Despite their high WSF, these products account for only 3% of the imports by mass confirming the relevance of impact based water footprint assessments. Country-wise, main contributors change along the analysed years. In the year 2000, one-quarter of the WSF occurs in Uzbekistan due to cotton imports. Afterwards, the highest WSF arises in Iran and Spain, while the imports from the US dominate the WSF in 2015. The changing trend follows the pattern of production of the hotspots identified on the product level, e.g. nuts, soybeans, and cotton. This study provides information on the water scarcity impacts that the German consumption creates in other countries and may be useful for decision-making processes aiming at optimising water scarcity footprints.

Psychometric characteristics of the Spanish version of instruments to measure neck pain disability.

BACKGROUND: The NDI, COM and NPQ are evaluation instruments for disability due to NP. There was no Spanish version of NDI or COM for which psychometric characteristics were known. The objectives of this study were to translate and culturally adapt the Spanish version of the Neck Disability Index Questionnaire (NDI), and the Core Outcome Measure (COM), to validate its use in Spanish speaking patients with non-specific neck pain (NP), and to compare their psychometric characteristics with those of the Spanish version of the Northwick Pain Questionnaire (NPQ). METHODS: Translation/re-translation of the English versions of the NDI and the COM was done blindly and independently by a multidisciplinary team. The study was done in 9 primary care Centers and 12 specialty services from 9 regions in Spain, with 221 acute, subacute and chronic patients who visited their physician for NP: 54 in the pilot phase and 167 in the validation phase. Neck pain (VAS), referred pain (VAS), disability (NDI, COM and NPQ), catastrophizing (CSQ) and quality of life (SF-12) were measured on their first visit and 14 days later. Patients' self-assessment was used as the external criterion for pain and disability. In the pilot phase, patients' understanding of each item in the NDI and COM was assessed, and on day 1 test-retest reliability was estimated by giving a second NDI and COM in which the name of the questionnaires and the order of the items had been changed. RESULTS: Comprehensibility of NDI and COM were good. Minutes needed to fill out the questionnaires [median, (P25, P75)]: NDI. 4 (2.2, 10.0), COM: 2.1 (1.0, 4.9). Reliability: [ICC, (95%CI)]: NDI: 0.88 (0.80, 0.93). COM: 0.85 (0.75,0.91). Sensitivity to change: Effect size for patients having worsened, not changed and improved between days 1 and 15, according to the external criterion for disability: NDI: -0.24, 0.15, 0.66; NPQ: -0.14, 0.06, 0.67; COM: 0.05, 0.19, 0.92. VALIDITY: Results of NDI, NPQ and COM were consistent with the external criterion for disability, whereas only those from NDI were consistent with the one for pain. Correlations with VAS, CSQ and SF-12 were similar for NDI and NPQ (absolute values between 0.36 and 0.50 on day 1, between 0.38 and 0.70 on day 15), and slightly lower for COM (between 0.36 and 0.48 on day 1, and between 0.33 and 0.61 on day 15). Correlation between NDI and NPQ: r = 0.84 on day 1, r = 0.91 on day 15. Correlation between COM and NPQ: r = 0.63 on day 1, r = 0.71 on day 15. CONCLUSION: Although most psychometric characteristics of NDI, NPQ and COM are similar, those from the latter one are worse and its use may lead to patients' evolution seeming more positive than it actually is. NDI seems to be the best instrument for measuring NP-related disability, since its results are the most consistent with patient's assessment of their own clinical status and evolution. It takes two more minutes to answer the NDI than to answer the COM, but it can be reliably filled out by the patient without assistance. TRIAL REGISTRATION: Clinical Trials Register NCT00349544.